Indicator for electric circuits



(No Model.)

0. B. (SHALLENBERGER.

INDIGATOR FOR ELECTRIC CIRCUITS.

No. 394,728. Patented Dec. 18, 1888.

IIIHTI llllllllll II WITNESSES:

UNITED STATES PATENT OFFICE.

' lnlnmmmm OLIVER B. SHALLENBERGER, OF ROCHESTER, ASSIGNOR TO THE '\VESTING- HOUSE ELECTRIC COMRANY, OF PITTSBURG, PENNSYLVANIA.

INDICATOR FOR ELECTRIC CIRCUlTS.

SPECIFICATION forming part of Letters Patent No. 394,728, dated December 18, 1888.

Application filed October 11, 1888. Serial No. 287,846. (No model-J To all whom it may concern: oid. If a spring or weight is employed to Be it known that I, OLIVER B. SHALLEN- oppose the pull of the solenoid and the cur- BERGER, a citizen of the United States, rerent through the solenoidis gradually dimina which the following is a specification. nearly constant; over a considerable distance siding in Rochester, in the county of Beaver ished, the core will be gradually withdrawn 55 and State of Pennsylvania,have invented cerfrom the solenoid; but the position in which tain new and useful Improvements in Indiit will be most sensitive to a given decrease cators for Electric Circuits, (Case No. 224,) of of current is that in which the pull remains The invention relates to the construction for a given current, and this position corre- 6o of meters for indicating the difference of posponds to that in which the maximum pull is tential or the current flowing upon an elecexerted. In other positions it will respond tric circuit. much less readily to a given change of cur- The object of the invention is to provide rent. an indicator of this character in which the In the diagram, Fig. 1, let the verticles .r 65 variations in the pull exerted shall be di- 00 00 drawn from the normal N N, represent rectly proportional to the variations in curdiiferent positions of a core in a solenoid, rent flowing through a very wide range of and the curved line 0 the value of the atmovement. traction exerted upon it in the different posi- The invention consists in so organizing two tions. \Vhen the core extends through the 7o 2o solenoids and theirrespective cores that when solenoid or is in a position of equilibrium,

one core'is in a position to be acted upon by the line 0 touches the normal N at w. Then its solenoid with a maximum effect the other as the core is withdrawn the line of rises from core is approaching a corresponding position the normal and attains a maximum at As with reference to its solenoid, and as the first the core is furtherwithdrawn, the line 0 again 75 2 5 core passes beyond the point of maximum approaches the normal and touches itat 00 effect the second core reaches its position of at which point the core is practically removed maximum effect, so that the increase of atfrom the field of the solenoid. Now it is traction upon one core will compensate for evident that the position of greatest sensithe decrease of attraction upon the other tiveness lies between the lines as and 00 8o core. where the maximum pull is exerted. In In the accompanying drawings, Figure 1 is practice, therefore, it has been customary to a theoretical diagram designed to illustrate so construct electric indicators as to utilize the variations in the attraction exerted upon the movements of the core through only this the two cores in the different positions which portion of the field when accurate measure- 85 5 they may bear with reference to their magment is required. If the current is such as netizing-solenoids, and Fig. 2 is a diagram to bring the core outside of these limits, a illustrating apparatus for carrying out the given variation in the current will have a invention. much less effect upon the core. If, now, a

It is well known that when acore is moved second solenoid and its core be so related 0 into and out of a solenoid traversed by an to the one just described that it is brought electric current the degree of attraction or into action at the time the pull upon the b pull exerted differs according to the differfirst core commences to diminish, then its ent positions occupied by the core. Thus if curve of pull may be represented by the line the core is extended entirelythrough thesolen- 0 which is in every respect similar to the 5 oid it is in a posit-ion of equilibrium and no line 0, except in its location upon the normal pull is exerted; but as it is gradually with- N N. The sum of these two curves is repre drawn the pull increases gradually to a maxisented by the dotted line 0. If, therefore, the mum.- It then remains approximately constant two cores be secured to a common support, L through a certain distance, and afterward the line 0 will represent the resultant pull ex- 100. gradually decreases until the core is entirely erted upon that support, and it is evident that removed from the magnetic field of the solar. the range of sensitiveness is prolonged from the line 91; to the line y, and that between the lines 915 and y the degree of pull exerted is approximately constant, and it the motion be opposed by a sprin the movement of the support will be a mroximately proportional to the variation in the current.

Referring now to Fig. 2, let A A represent two solenoids, which are in this instance included in series in a conductor, 1), between points] and 2 in an electric circuit. 'lhcy may, however, be connected in multiple are. The solenoids are r(.-s]')ectively provided with soft-iron cores o (L2, which may with advantage be composed of magnetically separated soft-iron wires, especially so in case the indicator is to be used with alternating electric currents. The cores here shown are supported at the respective ends of a pivoted beam, l and they are curved in such a manner as to enter their respective solenoids when the beam is turned upon its axis 1) in the proper direction. A retractile spring, .9, and adjusts ing ('l-eviee s, or their equivalents, are employed to oppose the attraction of the solenoids. The two cores are so located with reference to each other and their respective solenoids that the curves of their attractions correspond to the lines 1; and Fig. j1.tliat is to say, as the core a is passingthrough the position of maximum magnetic eti'eet with reference to the solenoid A the core a is approaching a corresponding position with reterenee to the solenoid A The effect of this :is to cause the variz'ititm in the resultant pull exerted upon the beam 1 to be :qvproximately constant for every given increase or decrease of current flowing tluioug'h the solenoidslwtween certain limits of position, and there is also an equal sensit iveness on thcpartot' the with reference to its solenoid while the other is approachingand entering the position ot' maximum attraction with reference to its solenoid, and an indicator actuated by the mm ements of the cores.

2. An indicator for electriccurrents, consisting" ot' assisting" solenoids connected in an electric circuit, two cores respectively applied 1 then-etc, a support common to both cores, and an indicator actuated, thereby, one of said cores normally projecting into its solenoid a greater distance than the other.

1-3. In an indicator for electric. circuits, two

solenoids and two cores respectively actuated by said solenoids, one of said cores being normally situated in aposition of greater magnetic attraction than the other with reference to its solenoid.

In testimtmy whereof I have. hereunto subscribed my name this 2d day of October, A. l). 1888.

OLIVER l3. SIIALLEl BERGER.

Wit nesses:

W. l'). Ur'rnonAru, (I HARLES A. Tone r. 

